A. Field of the Invention
The present invention relates to drumheads for drums or similar musical instruments. More particularly, the invention relates to an improved drumhead having increased resistance to denting or damage by drumstick impact.
B. Discussion of Background Art
Drums are perhaps one of the most ancient types of musical instruments. They constitute an essential element in most classical and modern musical ensembles.
Originally, drumheads were made almost exclusively of animal skins, such as calfskin. Modernly, drumheads are fabricated from thin sheets of synthetic plastic. That material was substituted for natural animal skins in an effort to make possible the production of large volumes of drumheads of uniform qualities and lower cost than the natural materials, and to avoid some of the more undesirable qualities of natural drumheads, such as moisture absorbitivity.
Replacement of animal skin drumheads by those made from synthetic plastic sheets was not without disadvantages. For example, polyester films were found to be one of the strongest and most desirable synthetic drumhead materials, yet still possessing inherent limitations limiting the usefulness of that material.
One type of saturated-thermoplastic type polyester film which has been used extensively as a synthetic drumhead material is the condensation polymer of ethlyene glycol and terephthalic acid which has been formed into a thin film by biaxial stretching. Such polyester films are available commercially from the E. I. Dupont de Nemours & Co., Inc., under the trademark MYLAR. This material has high strength, good weatherability, and reasonable tonal qualities. And yet, while such polyester film is one of the strongest available synthetic drumhead materials, it is subject to denting or tearing in response to drumstick impact. Thus, the useful life of a polyester film drumhead in some relatively severe applications, such as "Rock" bands, can be as short as one hour or less.
Because of the cost and inconvenience associated with frequent replacement of dented or torn drumheads made of polyester film, various means have been tried to minimize the damage to the drumheads by drumstick impact. For example, Hartry, in U.S. Pat. No. 4,308,782, Jan. 5, 1982, discloses a drumhead in which a randomly oriented synthetic fabric material is laminated to the upper, impact surface of polyester film to form a laminated drumhead which is stated to have a reduced tendency to dent. U.S. Pat. No. 4,362,081, Dec. 7, 1982, also issued to Hartry, discloses a laminated drumhead in which polyester films are adhered to either side of a synthetic fabric material woven from a fiber yarn. The fabric material is stated to be the primary tension load carrier, and thereby to reduce the incidents of drumhead fracture.
In both of the above-identified patents, the entire drumhead is laminated with the specified materials, producing a sound quality substantially different from that achievable with an un-laminated polyester film.
Other attempts have been made to improve the impact resistance and useful life of polyester film drumheads. These include the lamination of a thin disc of vinyl, typically 0.006 inch thick, with a 0.0015 inch thick cover of polyester film, to the center of a drumhead made of polyester film. In our tests of drumheads so fabricated, we have found that the thin polyester film top lamination layer wears away and peels away after a relatively short playing time. Since vinyl is a very soft plastic, once the thin, harder polyester film layer wears away, impact of drumsticks quickly wears away the underlying polyester film. Thus, whatever resistance to drumhead or tearing might be afforded by this method of drumhead construction is very short lived. Moreover, the combination of polyester film and vinyl film in a laminated disc inhibits the natural frequency response of the drumhead. The result is a muffled mixture of unpleasing sound frequencies.
Another drumhead construction used in an effort to extend drumhead life consists of a disc of 0.007 inch-thick solid polyester film laminated to the upper center portion of a polyester film drumhead. In our tests of drumheads so construction, we found that after a short playing time, the overlying polyester film disc cracked and dented, offering little or no protection to the drumhead from denting or breaking. Moreover, the thickness of the polyester film lamina reduced the volume and frequency response of the drumhead. The present invention was conceived of to provide improved drumhead performance while avoiding some of the limitations of prior art drumhead strengthening modifications.